Any Hydra parameter can be a function of time, enabling continuous animation without retyping code

Instead of a static number, any Hydra parameter accepts a JavaScript function — typically an arrow function — that returns a value at each frame. The global variable time holds milliseconds elapsed since page load, enabling sine waves, ramps, or any time-varying expression. osc(() => 100 * Math.sin(time * 0.1)) makes the oscillator frequency oscillate smoothly. This pattern replaces animation loops with declarative live-coding: a single re-evaluated expression stays alive until overwritten. The function is called every render frame, so it reacts in real time.

Examples

osc(() => (100 * Math.sin(time * 0.1))).out()

Assessment

Write a Hydra line where both frequency and rotation angle vary as different functions of time. Explain why using a function is preferable to periodically re-running a static snippet.